Increasing db_cache_size
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  1. #1
    Join Date
    Jul 2006
    Posts
    195

    Increasing db_cache_size

    I want to increase the size of the parameter db_cache_size from 1008M to
    2048M in order to get better hit ratio.

    SQL> show parameter db_cache_size;

    NAME TYPE VALUE
    db_cache_size big integer 1008M


    SQL> show sga

    Total System Global Area 2147483648 bytes
    Fixed Size 2085424 bytes
    Variable Size 1073745360 bytes
    Database Buffers 1056964608 bytes
    Redo Buffers 14688256 bytes

    SQL> show parameter sga

    NAME TYPE VALUE

    lock_sga boolean FALSE
    pre_page_sga boolean FALSE
    sga_max_size big integer 2G
    sga_target big integer 0


    My question is, if sga_max_size is set at 2G, would I be able to increase my db_cache_size to 2GB or do I need to first increase my sga_max_size first. Or to re-phrase, how is sga_max_size set, is
    it calculated or does it need to be manually set. I'm thinking its calculated because I dont see this in my spfile.


    I am running on a 64 bit AIX 5.3 machine on version 10.2.0.4 with 50GB
    of memory on this machine. So raising this value 1GB would not cause my performance to degrade.

    Thanks to all who answer
    Last edited by BeefStu; 01-12-2011 at 01:26 PM. Reason: fixed typo

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